1. Field of the Disclosure
This disclosure relates to a liquid crystal display device adapted to control a luminance of backlight unit according to a brightness of each divisional region of image, and a driving method thereof.
2. Description of the Related Art
As the information society grows, display devices capable of displaying information have been widely developed. These display devices include liquid crystal display (LCD) devices, organic electro-luminescence display devices, plasma display devices, and field emission display devices. Among the above display devices, the LCD devices have advantages that they are light and small and can be driven with low power drive and provide a full color moving image. Accordingly, the LCD devices have been widely used for mobile phones, navigation systems, portable computers, televisions and so on.
FIG. 1 is a block diagram schematically showing an LCD device of the related art. Referring to FIG. 1, the LCD device includes a timing controller 1, a gate driver 2, a data driver 3, a liquid crystal panel 4, a backlight controller 5, a backlight driver 6, and a backlight unit 7.
The timing controller 1 receives control signals, such as a vertical synchronous signal, a horizontal synchronous signal, a data enable signal, and others, together with a data signal, from the exterior. From the vertical and horizontal synchronous signals and the data enable signal, the timing controller 1 derives first control signals for driving the gate driver 2 and second control signals for driving the data driver 3. Moreover, the timing controller 1 generates a backlight control signal for driving the backlight unit 7.
The first control signals enable the gate driver 2 to apply scan signals to the liquid crystal panel 4. The second control signals also enable the data driver 3 to convert the data signal into an analog data voltage and to apply the converted analog data voltage to the liquid crystal panel 4.
The backlight controller 5 generates a backlight drive signal in accordance with the backlight control signal and applies the backlight drive signal to the backlight driver 6. The backlight driver 6 supplies the backlight unit 7 with a drive voltage derived from the backlight drive signal. The backlight unit 7 irradiates a light in correspondence with to the drive voltage to the liquid crystal panel 4.
The liquid crystal panel 4 displays an image on the basis of the refractive index of a liquid crystal which is interposed between two substrates. More specifically, the liquid crystal panel 4 varies the refractive index of the liquid crystal along with the analog data voltage and allows a transmissive amount of light, which is transmitted from the backlight unit 7 through it, to be adjusted in accordance with the refractive index of the liquid crystal, thereby displaying the image.
In this manner, the related art LCD device allows the light of uniform luminance to be irradiated to the entire surface of the liquid crystal panel, regardless of whether the image has regions must be more brightly or darkly displayed. Accordingly, the image on the liquid crystal panel can not be more brightly or darkly displayed in certain regions. As a result, the related art LCD device decreases the contrast ratio and furthermore deteriorates the visual discernment of the image.